1. Field of the Invention
This invention relates to a sample holding chuck for a chemical reactor and to a reactor assembly utilizing the chuck. More particularly, it relates to such a chuck which when rotated produces excellent mixing and agitation of the fluid in the reactor.
2. Background Art
In the production of semiconductor devices, small features are produced by processes involving photolithography, chemical etching, cleaning and drying. One cleaning process that has emerged as being particularly important is the use of a mixture of supercritical carbon dioxide and a co-solvent in a chemical reactor to clean articles such as semiconductor wafers that are being transformed into electronic devices.
One company that makes an apparatus in which, with suitable modifications, such cleaning operations may be performed is PARR Instruments of Moline, Illinois.
The PARR Instrument Reactor Bomb includes a shaft mounted paddle assembly which may be rotated by an external motor to stir the fluid within the vessel. A silicon chip to be cleaned may be mounted on a platform in spaced relation below the paddle. While adequate for many applications, this arrangement has the disadvantage of leaving a dead space of relatively unagitated fluid between the paddle and the wafer. For critical applications, such as the development and production of microelectronic devices, where the presence of any impurity may prove to be disastrous, this does not produce enough agitation of the fluid to adequately clean the samples. A better approach is required.
It is an object of the invention to provide an apparatus for thoroughly agitating a fluid in a chemical reaction vessel.
It is another object of the invention to provide an apparatus which efficiently carries away impurities as soon as they are removed from a sample being processed.
In accordance with the invention, a chuck assembly for holding a sample comprises a shaft; a generally circular chuck member, the shaft extending from a first surface of the chuck member; a sample holder associated with a second surface of said chuck member, the second surface being opposite the first a surface; and a sample receiving assembly for holding the sample on the sample holder so that the sample remains fixed to the sample holder when the shaft rotates and causes the chuck member and sample holder to rotate with the shaft. The chuck member has, at its periphery means for propelling a fluid. Further, the chuck member may be generally shaped as a squat cylinder with a plurality of grooves, the grooves extending along an outer surface of the cylinder, the grooves being at an acute angle with respect to a longitudinal axis of the chuck member. Further, in accordance with the invention, the chuck member has a plurality of openings extending therethrough in a direction parallel to a longitudinal axis of said chuck member.
Also in accordance with the invention, the chuck assembly may be combined with a reactor chamber for receiving the chuck assembly, a spindle assembly for receiving an end of the shaft distal from the chuck member; and a motor for rotating the spindle assembly and the shaft so that the fluid flows generally along the shaft in a first direction and through said openings in the chuck member, around said sample holder, and then along a wall of the chamber in a second direction generally opposite to the first direction. Preferably, the chamber is cylindrical and the fluid flows along a wall of the chamber in the second direction. There is preferably a first opening through which the reaction fluid is introduced into the chamber; and a second opening through which the reaction fluid is removed from said chamber. The first opening is disposed proximate the shaft and the second opening is disposed proximate the wall of the chamber.
A temperature control means is provided for controlling the temperature of the reactor chamber. The temperature control means may comprise a mantel surrounding the reactor chamber; and a controller for controlling the temperature of said mantle.
The sample receiving assembly may comprise at least one clip for holding the sample to the sample holder. The sample holder may have a plurality of through holes formed therein. At least one of the through holes receives a fastener for securing the clip to the sample holder.
The apparatus may further comprise a pressurizing apparatus for pressurizing said reactor chamber to a pressure of up to 10,000 psi.